1. Field of the Invention
The present invention relates to railway wheels with low acoustic emission.
2. Discussion of the Background
In contact with the rail on which it runs, a railway wheel is excited in vibration which causes it to emit a running noise, the power and frequency spectrum of which depend on the design of the wheel, on the finish of the contacting surfaces and on the speed of the train; in particular, for high-speed trains, the power of the noise emitted is very high and may reach 85 acoustic dB for speeds above 250 Km/h.
In fact, a railway wheel is a component intended for a specific application. For each application, the wheel is the subject of a specific design which takes account of the geometrical constraints, constraints of load per axle to be withstood and constraints of behavior under braking. However, constraints of acoustic emission are not taken into account, and this results in the wheels generally being very resonant.
In order to overcome this drawback, various techniques have been proposed which consist in locating resonators or dampers on the wheel, which interfere with the wheel, modify its natural vibrational frequencies, and decrease the acoustic emission.
These techniques exhibit the drawback of requiring fine adjustments of the resonators or of the dampers as a function of the natural frequencies of the wheel, and these natural frequencies vary each time the running surface is refreshed by machining. As a result, each wheel must be adjusted each time it is remachined.
In any case, these techniques are makeshift.